| TL Enterprises Limited | Real estate | 2022 |
| Tmont Limited | Information & communication | 2015 |
| TNC Psychiatry and Neuroscience Ltd | Health & social care | 2023 |
| TNG Cloud Solutions Ltd | Information & communication | 2026 |
| TNJ Pipe Clips Limited | Construction | 2009 |
| TNR Architects Limited | Professional & scientific | 2018 |
| TO the Line Brickwork Ltd | Construction | 2021 |
| TOD Butler Ltd | Professional & scientific | 2017 |
| Todd & O'Brien Limited | Financial services | 2022 |
| TOM Fleming Golf Limited | Wholesale & retail | 2025 |
| TOM Glass Limited | Manufacturing | 2002 |
| Tombell Anaesthesia Ltd | Health & social care | 2023 |
| Tomley Projects Ltd | Construction | 2021 |
| Tonara Services Ltd | Health & social care | 2025 |
| Tonnes Away Limited | Water & waste | 2019 |
| Tony Barker Transport Limited | Transport & logistics | 2012 |
| Tony Carter Associates Limited | Professional & scientific | 2009 |
| Top Class Computers (UK) Limited | Information & communication | 2001 |
| Top Exterior Solutions Ltd | Construction | 2026 |
| Top GUN Racing Limited | Administrative & support | 2021 |
| Top Trade (UK) Corporation Limited | Real estate | 2017 |
| Top Trade Oxford Limited | Real estate | 2021 |
| Tops N Tails Dog Groomers Ltd | Other services | 2025 |
| Topsport (Sports Goods) Limited | Wholesale & retail | 1975 |
| Tornado Marketing Limited | Professional & scientific | 2008 |
| Torque (Oxford) Ltd | Wholesale & retail | 2023 |
| Torrance Windfarm LLP | | 2012 |
| TOS Learning Ltd | Education | 2023 |
| Total Access Audio Systems Limited | Professional & scientific | 2017 |
| Total Carpentry (Oxford) Limited | Construction | 2012 |
| Totally Safe Ltd | Professional & scientific | 2020 |
| Touchstone Partners Limited | Professional & scientific | 2002 |
| Towgo Ltd | Wholesale & retail | 2026 |
| Town and Country Trees Limited | Agriculture & fishing | 2001 |
| Townsend Brothers Limited | Construction | 2010 |
| Townside Court (Reading) Management Company Limited | Households | 2013 |
| Toyaga Ltd | Hospitality | 2016 |
| TPC Witney Limited | Financial services | 2009 |
| TPT Consultancy Ltd | Health & social care | 2022 |
| TPZ Group Ltd | Wholesale & retail | 2019 |
| Trackforward Ltd | Professional & scientific | 2024 |
| Trade Building Plastics Ltd. | Wholesale & retail | 2000 |
| Trade Labour Company Ltd | Construction | 2023 |
| Traditional Garden Growers Ltd | Agriculture & fishing | 2022 |
| Tranquility Counselling Ltd | Health & social care | 2025 |
| Translate Digital Marketing Ltd | Professional & scientific | 2020 |
| Travel Industry Finance Limited | Administrative & support | 2024 |
| Traveltrix Ltd | Wholesale & retail | 2022 |
| Treasure Family Limited | Real estate | 2021 |
| Treasure Labs Ltd | Information & communication | 2025 |
| Trebble Trading Limited | Transport & logistics | 2023 |
| Trebor Productions Limited | Information & communication | 2019 |
| Treemendously Wild CIC | Education | 2022 |
| Trees and Gardens Ltd | Administrative & support | 2005 |
| TRH Property Ltd | Real estate | 2023 |
| Tribelogic Consulting Ltd | Information & communication | 2018 |
| Triple C Motorcycles Limited | Wholesale & retail | 2018 |
| Triple E Property Ltd | Real estate | 2019 |
| Triverde Limited | Real estate | 2024 |
| Tropiglaze Limited | Construction | 2006 |
| Truck Enterprises Limited | Real estate | 2025 |
| Truck Music Store Limited | Wholesale & retail | 2013 |
| Truckexp Ltd | Transport & logistics | 2023 |
| True Holdings Group Ltd | Financial services | 2024 |
| True North Research Ltd | Professional & scientific | 2021 |
| Trueleads Ltd | Professional & scientific | 2020 |
| Truemans of Oxford Limited | Wholesale & retail | 1982 |
| Trustin Foods UK Limited | Wholesale & retail | 2005 |
| Trywin Games Ltd | Arts & recreation | 2019 |
| TT Concrete Products Limited | Manufacturing | 2003 |
| Tudorbury Limited | Professional & scientific | 2024 |
| Tumblebug Limited | Agriculture & fishing | 2020 |
| Tumbling Bay Cafe Ltd | Hospitality | 2021 |
| Tuned Consulting Limited | Information & communication | 2011 |
| Tupoe Ltd | Professional & scientific | 2019 |
| Turn IT on Limited | Information & communication | 2003 |
| Turn IT on Trustees Limited | Information & communication | 2015 |
| Turner & Turner Co. (UK) Limited | Real estate | 2025 |
| Turners Property Witney Ltd | Financial services | 2024 |
| Turnkey Future Homes Ltd | Real estate | 2026 |
| Tusk Dental Technologies Ltd | Manufacturing | 2010 |
| Tustins Group Limited | Agriculture & fishing | 2019 |
| TW Hardscaping Ltd | Construction | 2013 |
| TW Haulage (Witney) Limited | Extraterritorial | 2024 |
| TW Hire Ltd | Administrative & support | 2025 |
| Twin Peaks Real Estate Ltd | Extraterritorial | 2018 |
| Twinklean Limited | Administrative & support | 2014 |
| TWM Financial Partners Ltd | Financial services | 2024 |
| Two B'S Coffee Co Ltd | Manufacturing | 2022 |
| Two Kings Tattoo Studio Ltd | Arts & recreation | 2024 |
| Two Red Sevens Limited | Wholesale & retail | 2013 |
| Two Rivers Holdings Ltd | Financial services | 2019 |
| Two Tails Ltd | Information & communication | 2010 |
| Two's Company Hair & Beauty Ltd | Other services | 2007 |
| Tyler Aeronautica Ltd | Transport & logistics | 2006 |
| Tyler Thomson Transport Ltd | Transport & logistics | 2016 |
| Type Rain Limited | Information & communication | 2023 |
| Tyred Format Ltd | Professional & scientific | 2022 |
| U.K.-Canada Trading Company Limited | Construction | 1966 |
| Ucantlose Limited | Information & communication | 2003 |